KR102433174B1 - Method and apparatus of high purity sodium bicarbonate production using flue gas - Google Patents

Abstract

The present invention relates to an apparatus and method for producing high-purity sodium bicarbonate by reacting carbon dioxide contained in exhaust gas generated after combustion with sodium carbonate.
An apparatus for producing high-purity sodium bicarbonate using an exhaust gas according to the present invention includes a reaction tank (10); a solution inlet 11 through which an aqueous sodium carbonate solution is introduced from the outside into the upper portion of the reaction tank 10; a gas inlet 12 through which a gas containing carbon dioxide is introduced from an exhaust line through which combustion exhaust gas is discharged to a lower portion of the reaction tank 10; and a diffusion plate 15 disposed in the reactor 10; In the reactor 10, the sodium carbonate aqueous solution flows from the top to the bottom, and the gas flows from the bottom to the top to form sodium bicarbonate, a reactant of the sodium carbonate and the carbon dioxide, but the diffusion plate 15 ) is wider toward the bottom, characterized in that it increases the reaction of the sodium carbonate aqueous solution and the carbon dioxide diffused by the diffusion plate (15).

Description

High-purity sodium bicarbonate manufacturing apparatus and manufacturing method using flue gas

The present invention relates to an apparatus and method for producing high-purity sodium bicarbonate by reacting carbon dioxide contained in exhaust gas generated after combustion with sodium carbonate.

In thermal power generation, exhaust gases are generated after combustion of fossil fuels.

These exhaust gases contain harmful substances or greenhouse gases that cause global warming, and thus the exhaust gases are required to be purified.

As one of the technologies for treating the greenhouse gas contained in the exhaust gas, that is, carbon dioxide, a carbon capture and storage technology (CCS, Carbon Capture and Storage) technology for capturing and storing the carbon dioxide is applied.

However, the carbon dioxide capture and storage technology requires a lot of cost to capture and store the carbon dioxide, and the captured and stored carbon dioxide cannot be recycled.

KR 10-2002479 B1 (2019.07.16, name: high purity 　 sodium bicarbonate 　 manufacturing system)

The present invention was invented to solve the above problems, and high-purity bicarbonate using an exhaust gas that allows the production of high-purity sodium bicarbonate by reacting carbon dioxide contained in the flue gas generated after thermal power generation using fossil fuels with sodium carbonate. An object of the present invention is to provide an apparatus and method for producing sodium.

A high-purity sodium bicarbonate production apparatus using an exhaust gas according to the present invention for achieving the above object, a reaction tank; a solution inlet through which an aqueous sodium carbonate solution is introduced into the upper portion of the reactor from the outside; a gas inlet through which a gas containing carbon dioxide is introduced from an exhaust line through which combustion exhaust gas is discharged to a lower portion of the reaction tank; and a diffusion plate disposed in the reaction tank, wherein in the reaction tank, the sodium carbonate aqueous solution flows from the top to the bottom, and the gas flows from the bottom to the top while sodium bicarbonate, a reactant of the sodium carbonate and the carbon dioxide, is formed characterized in that

The height of the reaction tank is characterized in that it is formed to be 10 to 20 times the width or diameter of the reaction tank.

It is characterized in that a gas outlet through which the gas from which the carbon dioxide is removed is formed higher than the solution inlet in the reaction tank.

It is characterized in that the slurry outlet through which the slurry containing the sodium bicarbonate is discharged is formed at the lower end of the reactor.

The concentration of the aqueous sodium carbonate solution introduced into the solution inlet is 30% to 40%.

Between the exhaust line and the gas inlet, a cooler for cooling the gas and a water remover for removing moisture contained in the gas that has passed through the cooler are sequentially provided.

The diffusion plate is characterized in that in order to control the rate at which the gas rises and to disperse the precipitated sodium bicarbonate sludge, the upper part is closed and the width is formed to become wider toward the lower part.

The diffusion plate is characterized in that a plurality of diffusion plates are arranged in parallel to each other in a direction perpendicular to the longitudinal direction of the reactor.

The diffusion plate is characterized in that it is arranged to be stacked in a plurality of stages along the longitudinal direction of the reactor.

The diffusion plates adjacent to each other vertically are arranged to cross each other perpendicularly.

A circulation line for circulating a portion of the solution filled in the reaction tank is formed on one side, and a heat exchanger for heating the solution circulating the circulation line is installed in the circulation line.

The heat exchanger is characterized in that the solution is heated to 40 °C to 45 °C.

The diffusion plate has a wider width toward the bottom, and the reaction between the aqueous sodium carbonate solution and the carbon dioxide diffused by the diffusion plate is increased.

On the other hand, the method for producing high-purity sodium bicarbonate using an exhaust gas according to the present invention includes a sodium carbonate aqueous solution introducing step of introducing an aqueous sodium carbonate solution into the reactor through the upper part of the reactor in which a diffusion plate formed to become wider toward the bottom is disposed, and and introducing a gas containing carbon dioxide discharged through an exhaust line through which combustion exhaust gas is discharged into the inside of the reaction tank through a lower portion of the reaction tank, wherein the sodium carbonate aqueous solution and the carbon dioxide are mutually transferred in the reaction tank By flowing in opposite directions to prepare sodium bicarbonate, which is a reactant of the sodium carbonate and the carbon dioxide, the reaction between the aqueous sodium carbonate solution and the carbon dioxide diffused by the diffusion plate is increased.

After the step of introducing the sodium carbonate aqueous solution, the method further comprises a gas cooling step of cooling the gas flowing into the reactor.

After the gas cooling step, it characterized in that it further comprises a water removal step of removing the water contained in the cooled gas.

The concentration of the sodium carbonate aqueous solution introduced in the sodium carbonate aqueous solution introduction step is 30% to 40%.

After the gas inlet step, while circulating the reactants in the reaction tank through a circulation line, the method further comprises a reactant heating step of heating the reactants with a heat exchanger installed in the circulation line.

The reactant heating step is characterized in that the reaction tank is heated to 40 °C to 45 °C.

It characterized in that it further comprises a slurry washing step of washing the slurry containing the sodium carbonate generated inside the reactor.

The slurry washing step is characterized in that washing with an aqueous sodium bicarbonate solution.

The sodium bicarbonate aqueous solution is characterized in that the weight ratio of sodium bicarbonate to the weight of the total aqueous solution is 7.7%.

According to the high-purity sodium bicarbonate manufacturing apparatus and manufacturing method using the flue gas of the present invention having the above configuration, by reacting the flue gas discharged after fossil power generation with an aqueous sodium carbonate solution, the carbon dioxide and sodium carbonate contained in the flue gas react to produce sodium bicarbonate do.

In addition, since the exhaust gas flows into the reactor in a state in which cooling and moisture have been removed, the precipitation of sodium bicarbonate is facilitated.

In addition, the reaction rate can be increased by heating the reactants in the reaction tank.

In addition, by washing with an aqueous sodium bicarbonate solution, it is possible to increase the purity of the final product.

1 is a schematic view showing a high-purity sodium bicarbonate manufacturing apparatus using an exhaust gas according to a first embodiment of the present invention.
Figure 2 is a graph showing the solubility of sodium carbonate and sodium bicarbonate.
3 is a schematic view showing an apparatus for manufacturing high-purity sodium bicarbonate using an exhaust gas according to a second embodiment of the present invention.
4 is a perspective view illustrating a state in which a diffusion plate is arranged in the apparatus for manufacturing sodium bicarbonate of FIG. 3;
5 is a schematic view showing an apparatus for manufacturing high purity sodium bicarbonate using an exhaust gas according to a third embodiment of the present invention.
6 is a schematic view showing an apparatus for manufacturing high-purity sodium bicarbonate using an exhaust gas according to a fourth embodiment of the present invention.
7 is a flowchart illustrating a method for manufacturing high-purity sodium bicarbonate using an exhaust gas according to the present invention.

Hereinafter, with reference to the accompanying drawings, a high-purity sodium bicarbonate manufacturing apparatus and manufacturing method using an exhaust gas according to the present invention will be described in detail.

The present invention utilizes a carbonation reaction process. Carbonation reaction process is a reaction in which carbon dioxide (CO ₂ ) reacts with sodium carbonate (Na ₂ CO ₃ ) and water (H ₂ O) to produce sodium bicarbonate (NaHCO ₃ ).

The chemical formula of the carbonation reaction is as follows.

Na ₂ CO ₃ (aq)+CO ₂ (g)+H ₂ O(l)→2NaHCO ₃ (aq)

The heat of reaction (ΔH), entropy (ΔS), and free energy (ΔG) of the carbonation reaction are as follows.

ΔH (kJ/mol) ΔS (kJ/mol K) ΔG (298 K) -129.09 -0.334 -29.56

[Table 1] Heat of reaction (ΔH), entropy (ΔS), free energy (ΔG) for each reaction in the carbonation reaction process

As can be seen from the table above, the reaction between sodium carbonate and carbon dioxide is an exothermic reaction and proceeds spontaneously at room temperature because the free energy is negative. However, since the absolute value of free energy is small, the reaction rate is slow and the calorific value is not large. Therefore, in order to increase the economic efficiency of the present process, it is most important to increase the efficiency of the carbonation reaction.

Therefore, the apparatus for producing high-purity sodium bicarbonate using the exhaust gas of the present invention is configured to increase economic efficiency in the carbonation reaction.

1 shows an apparatus 1 for producing high-purity sodium bicarbonate using an exhaust gas according to a first embodiment of the present invention.

The reaction tank 10 is formed in a cylindrical shape elongated in the vertical direction, so that the sodium carbonate reacts with the carbon dioxide in the reaction tank 10 to precipitate sodium bicarbonate in the form of a slurry.

The reaction tank 10 is formed in a cylindrical shape. The reactor 10 basically has a closed top so that the gas introduced therein does not flow out, and a closed bottom in order to store the sodium carbonate aqueous solution while reacting.

The reaction tank 10 is provided with a solution inlet 11 and a gas inlet 12 for introducing an aqueous sodium carbonate solution and carbon dioxide, which are raw materials for the carbonation reaction.

The height of the reaction tank 10 is formed to be 10 to 20 times the width or diameter of the reaction tank 10 . In this way, by forming the reaction tank 10 to be elongated in the vertical direction, the reaction time between sodium carbonate and carbon dioxide is increased, and the precipitation of sodium bicarbonate, which is a product, is increased.

The solution inlet 11 is formed on one side of the reaction tank 10 , preferably at an upper portion of the reaction tank 10 . Through the solution inlet (11), the sodium carbonate aqueous solution is introduced into the inside of the reaction tank (10). Since the solution inlet 11 is formed at the upper portion, the aqueous sodium carbonate solution introduced into the reaction tank 10 moves toward the lower portion of the reaction tank 10 . The concentration of the aqueous sodium carbonate solution introduced into the solution inlet 11 may be 30% to 40%.

The gas inlet 12 is spaced apart from the solution inlet 11 in the reaction tank 10 , and is formed in the lower part of the reaction tank 10 . The gas inlet 12 serves to introduce a gas including carbon dioxide into the reaction tank 10 . In the present invention, the gas inlet 12 is connected to the exhaust line of the thermal power plant so that exhaust gas generated by combustion in the thermal power plant is introduced into the reactor 10 .

The gas inlet 12 is formed in the lower portion, so that the exhaust gas containing carbon dioxide flows from the bottom to the top inside the reaction tank 10, and reacts with the sodium carbonate for carbonation. The exhaust gas moves upward, and the sodium carbonate aqueous solution moves downward, and the carbonation reaction proceeds while moving to face each other. At this time, since the solubility of sodium bicarbonate is much lower than the solubility of sodium carbonate (see FIG. 2), as the reaction proceeds, sodium bicarbonate is precipitated in the form of a slurry.

A gas outlet 13 is formed in the reaction tank 10 through which the exhaust gas from which carbon dioxide has been removed by completing the reaction in the reaction tank 10 is discharged to the outside. The gas outlet 13 is located higher than the solution inlet 11 , and is preferably formed at the upper end of the reaction tank 10 .

In addition, a slurry outlet 14 through which the slurry containing the sodium bicarbonate (NaHCO ₃ ) is discharged is formed at the lower end of the reactor 10 .

A valve for regulating the entry and exit of substances may be installed in the solution inlet 11 , the gas inlet 12 , the gas outlet 13 and the slurry outlet 14 , respectively, and the valve is controlled remotely can be

Meanwhile, during the carbonation reaction in the reaction tank 10 , in order to increase the purity of the sodium bicarbonate finally produced, it is necessary to remove the unreacted raw material sodium carbonate.

In the present invention, the sodium bicarbonate slurry is washed using the solubility difference between the two substances to produce high-purity sodium bicarbonate, and the washing solution containing sodium carbonate is again introduced into the reactor 10 . At this time, use a sodium bicarbonate solution rather than pure water to minimize the elution of sodium bicarbonate and wash only impurities such as sodium carbonate. For example, in water at 25°C, sodium bicarbonate and sodium carbonate mixture can be dissolved up to 7.7% and 5.6% by weight, respectively, so an aqueous solution having a sodium bicarbonate weight ratio of 7.7% to the total sodium bicarbonate weight as a washing solution is used to dissolve sodium bicarbonate The losses are minimized and only the sodium carbonate impurities can be removed by dissolving them. The washing solution used in this way further dissolves sodium carbonate as a raw material and injects it back into the reactor 10, so that even sodium carbonate, which has been removed as an impurity, can participate in the reaction again, so there is no loss of yield due to washing, and high-purity, high-grade sodium bicarbonate is produced. be able to do

3 shows an apparatus for manufacturing high-purity sodium bicarbonate using an exhaust gas according to a second embodiment of the present invention.

In this embodiment, it basically has the same structure as the sodium bicarbonate manufacturing apparatus 1 of the first embodiment, but the diffusion plate 15 is additionally formed therein.

The diffusion plate 15 controls the rate at which the gas including carbon dioxide rises by bypassing the diffusion plate 15 . In order to increase the reaction cross-sectional area and reaction space of the diffusion plate 15, the lower portion is open and the width is narrowed toward the upper portion and the upper portion is closed. The diffusion plate 15 is formed in plurality to increase the contact area and contact time between the aqueous sodium carbonate solution and carbon dioxide.

In a typical reactor, a packed bed reactor is installed inside to increase the reaction efficiency, but in this reaction, the slurry accumulates on the packing, which leads to a decrease in reaction efficiency. becomes this In order to avoid this, if a bubble column reactor without an internal packing is introduced, the clogging of the slurry can be avoided, but there is a disadvantage in that the reaction efficiency is lowered.

Therefore, the diffusion plate 15 is applied to solve this problem.

Referring to FIG. 4 , the shape and arrangement of the diffusion plate 15 will be described in detail as follows.

The diffusion plate 15 is formed such that the lower part is open, the upper part is closed, and the width increases toward the lower part. For example, the diffusion plate 15 may be formed in a cone shape with an empty lower portion and an inner portion. Preferably, it may be formed so that the middle portion is high by bending the plate material.

As shown in FIG. 3 , the diffusion plate 15 may be formed in a shape such as '∧', that is, an inverted V-shape such that the cross-section is wide at the bottom and narrows toward the top. The plate material is bent so that the middle portion is raised, so that the diffusion plate 15 is formed in an inverted V-shape (∧) so that both ends of the diffusion plate 15 are lowered. Both ends of the diffusion plate 15 in the longitudinal direction are formed adjacent to the inner surface of the reactor 10 .

A plurality of these diffusion plates 15 are arranged along a direction perpendicular to the longitudinal direction of the reactor 10 . This means that the diffusion plates 15 are arranged in a horizontal direction at substantially the same height. At this time, the diffusion plates 15 are arranged parallel to each other.

In addition, the diffusion plate 15 is arranged to be stacked in a plurality of stages along the longitudinal direction (up and down direction) of the reactor 10 . In particular, when the diffusion plate 15 is arranged along the longitudinal direction of the reactor 10, the diffusion plate 15 is arranged in a different direction from the other diffusion plates 15 adjacent vertically. For example, it is preferable that the diffusion plates 15 adjacent in the vertical direction cross each other in a direction perpendicular to each other (see FIG. 4 ).

When the diffusion plate 15 is arranged, a gap is formed from the other adjacent diffusion plates 15 so that gas or material can move through the gap.

As described above, since the diffusion plate 15 is formed in plurality in the horizontal and vertical directions, the exhaust gas containing the carbon dioxide stays in the lower part of the diffusion plate 15 for a while and bypasses the diffusion plate 15 to make the The process of ascending after passing through the periphery of the diffusion plate 15 is repeated to pass through the diffusion plate 15 to increase the reaction efficiency. That is, the reaction efficiency is improved by maximizing the contact area and gas holdup between the sodium carbonate and the carbon dioxide.

In addition, in the middle of the reaction tank 10, the product moves downward without being accumulated.

5 shows a high-purity sodium bicarbonate manufacturing apparatus 1 using an exhaust gas according to a third embodiment of the present invention.

In this embodiment as well, it has the same structure as the sodium bicarbonate production apparatus 1 of the first embodiment, but a heating means for heating the solution inside the reaction tank 10 is additionally provided.

In the sodium bicarbonate production process through the carbonation reaction, clogging may occur due to the precipitated slurry. If clogging occurs, the process must be stopped and washed by spraying high-temperature washing water, resulting in economic loss due to process interruption and slurry washing.

To prevent this phenomenon, a heating means is applied to one side of the reaction tank 10 .

When a part of the reactant inside the reaction tank 10 is circulated, the effect of preventing clogging by circulation can be expected.

In addition, by heating the reactant during circulation, the effect of improving the reaction rate can be expected.

To this end, a circulation line 16 for circulating the reactants inside the reaction tank 10 to the outside is formed on one side of the reaction tank 10 . The circulation line 16 discharges the reactants inside the reaction tank 10 from the lower side of the reaction tank 10 to return it to the reaction tank 10 .

In addition, a heat exchanger 23 for heating the reactants is provided in the circulation line 16 . The heat exchanger 23 increases the temperature of the reactants flowing along the circulation line 16 .

Through the heat exchanger 23, the temperature of the reactant is set to 40°C to 45°C. At the lower end of the reactor, that is, when the temperature of the reactant is 40° C. or less, the slurry may be precipitated in the circulation line 16 . In addition, if it is 45° C. or higher, energy may be consumed excessively.

Particularly preferably, the temperature of the reactants is 42°C. As shown in FIG. 2 , 42° C. is the point at which the difference in solubility between sodium bicarbonate and sodium carbonate is maximum.

In addition, in order to remove moisture from one side of the reaction tank 10, a cooler 21 and a water remover 22 are installed at a portion where the exhaust line of the thermal power plant and the gas inlet 12 of the reaction tank 10 are connected. Provided sequentially, the exhaust gas flowing into the reaction tank 10 is cooled and moisture is removed.

Typical combustion flue-gases contain approximately 20% to 40% steam. In this reaction, when 1 mole of carbon dioxide reacts, 1 mole of water (H ₂ O) also reacts to remove water, but if the moisture content in the flue gas is greater than carbon dioxide, the amount of water in the reaction tank 10 increases and the concentration of the reactant is dilute. lose When the concentration of the reactant becomes dilute, the precipitated amount of sodium bicarbonate as a product decreases, the process cost increases because a dehydration process must be added as a post-process, and a loss of sodium carbonate as a raw material occurs by the dehydration process. Therefore, the exhaust gas containing carbon dioxide is cooled through the cooler 21 before being introduced into the reactor 10, and the exhaust gas cooled by the cooler 21 passes through the water remover 22. By doing so, moisture contained in the flue gas flowing into the reaction tank 10 is removed. In this way, by maintaining the moisture contained in the flue gas flowing into the reaction tank 10 lower than the carbon dioxide contained in the flue gas, the dehydration process is unnecessary and the precipitation of sodium bicarbonate can be facilitated.

6 shows an apparatus 1 for producing high-purity sodium bicarbonate using an exhaust gas according to a fourth embodiment of the present invention.

In this embodiment, the diffusion plate 15 of the second embodiment and the heat exchanger 23, the cooler 21 and the moisture remover 22 of the third embodiment are all configured to be taken.

7 shows a method for producing high-purity sodium bicarbonate using the exhaust flue gas according to the present invention.

In the sodium carbonate aqueous solution introduction step (S110), the sodium carbonate aqueous solution is introduced into the reactor 10 through the upper part of the reactor 10 . The aqueous sodium carbonate solution introduced into the reaction tank 10 moves from the upper portion of the reaction tank 10 to the lower portion.

In the gas cooling step S120, the gas containing carbon dioxide is cooled. The cooler 21 is installed between the exhaust line of the thermal power plant and the gas inlet 12 to cool the gas.

In the water removal step (S130), water contained in the cooled gas is removed. The cooler 21 and the water remover 22 are installed between the exhaust line and the gas inlet 12 , and the gas that has passed through the cooler 21 is removed from the water by the water remover 22 . do.

In the gas introduction step ( S140 ), a gas containing carbon dioxide is introduced into the reaction tank 10 through the lower portion of the reaction tank 10 . The gas introduced in the gas introduction step (S140) becomes exhaust gas generated after combustion in a thermal power plant. After the exhaust gas is supplied through the exhaust line, it passes through the cooler 21 and the moisture remover 22, , is cooled and introduced into the reactor 10 in a state in which moisture is removed. When gas is introduced into the reaction tank 10 , the gas moves upward from the bottom of the reaction tank 10 .

In this way, when the sodium carbonate aqueous solution and the exhaust gas containing carbon dioxide are flowed in opposite directions into the reaction tank 10, the product sodium bicarbonate (NaHCO ₃ ) is generated through the carbonation reaction.

In the interior of the reaction tank 10, as described above, the efficiency is improved by increasing the connection area and gas retention of the sodium carbonate aqueous solution and the exhaust gas containing carbon dioxide by the diffusion plate 15.

On the other hand, sodium bicarbonate generated through the carbonation reaction moves to the lower end of the reaction tank 10 and is discharged to the outside, and the exhaust gas from which carbon dioxide is removed by the carbonation reaction is discharged to the outside through the upper end of the reaction tank 10. .

In addition, through the gas cooling step (S120) and the water removal step (S130), the gas is introduced into the inside of the reaction tank 10, the amount of moisture contained in the gas introduced into the reaction tank 10 Keep it below carbon dioxide. Accordingly, even if the reaction continues inside the reaction tank 10, the concentration of the reactant is prevented from being diluted, thereby facilitating the precipitation of sodium bicarbonate.

In the reactant heating step ( S150 ), the reactant in the reaction tank 10 is heated. By heating the reactants stored in the reaction tank 10 to a predetermined temperature, the efficiency of the carbonation reaction is improved. While the reactants are circulated through the circulation line formed on the lower side of the reaction tank 10 , the reactants pass through the heat exchanger 23 to heat the reactants to an appropriate temperature.

In the reactant heating step (S150), the reactant is preferably heated to 40°C to 45°C. More preferably, the temperature of the reactant is set to 42° C. at which the difference in solubility between sodium bicarbonate and sodium carbonate is maximized.

Meanwhile, in order to increase the purity of the sodium bicarbonate, a slurry washing step (S160) may be performed.

In the slurry washing step (S160), since sodium carbonate as an intermediate product remains in the reactor 10 due to a low reaction rate, it is removed to increase the purity of sodium bicarbonate.

In the slurry washing step (S160), the liquid is sprayed, and the sodium carbonate may be removed by using pure water or by spraying a sodium bicarbonate solution. In the case of spraying the sodium bicarbonate solution, the sodium bicarbonate aqueous solution preferably has a weight ratio of sodium bicarbonate to the weight of the total aqueous solution of 7.7%.

Either one of the reactant heating step ( S150 ) and the slurry washing step ( S160 ) may be selectively performed. In addition, the slurry washing step (S160) may be performed after the reactant heating step (S150) is performed, or the reactant heating step (S150) may be performed after the slurry washing step (S160) is performed.

Table 2 below shows examples of comparison of the carbon dioxide removal rate and the purity and yield of the produced sodium bicarbonate for each of the above-described Examples.

division CO2 Removal Rate Sodium Bicarbonate Purity Sodium Bicarbonate Yield Comparative Example 1 95% 97% 78% Comparative Example 2 99% 97% 80% Comparative Example 3 99% 99% 75% Comparative Example 4 98% 99% 85% Comparative Example 5 99% 98% 84% Comparative Example 6 97% 98% 89%

[Table 2] Carbon dioxide removal rate, sodium bicarbonate purity and sodium bicarbonate yield for each comparative example

In Comparative Example 1, the diffusion plate 15 is not installed inside the reaction tank 10, and an aqueous sodium carbonate solution is supplied to the upper portion of the reaction tank 10 and gas is supplied to the lower portion.

The reactor 10 is manufactured to have a height of 1,200 mm.

The sodium carbonate aqueous solution supplied to the inside of the reaction tank 10 has a concentration of 30 wt% of sodium carbonate, and is supplied at a flow rate of 45 mL/min.

The gas supplied into the reaction tank 10 is a mixed gas including carbon dioxide, and the concentration of the carbon dioxide in the mixed gas is maintained at about 14 volume ratio. Here, the reason why the volume ratio of carbon dioxide is maintained at about 14 volume ratio is that the volume ratio corresponds to the volume ratio of carbon dioxide included in the doubling water of the actual thermal power plant.

Meanwhile, the mixed gas is supplied at a flow rate of 25 litter/min, which corresponds to 10 kg/day and 10 kg of carbon dioxide treatment per day.

In addition, the reactant is heated to about 50° C. through the heat exchanger 23 and then circulated.

A measuring device is installed so that the temperature, pressure, pH, etc. inside the reaction tank 10 can be measured in real time, so that changes in the reactor with respect to variables generated during continuous operation can be measured.

Under such conditions, while supplying the sodium carbonate aqueous solution and the gas to the inside of the reaction tank 10,

The amount of carbon dioxide removal is measured by measuring the flow rate of the supplied gas, the flow rate of the discharged gas, and the carbon dioxide concentration. During operation, the circulation line 16 operates at a temperature of the lower end of the reactor below 40°C and stops at 45°C or higher. Sodium bicarbonate produced through the carbonation process is obtained in powder form through dehydration and drying processes. The continuous operation was carried out for about 5 hours, and the operation results such as carbon dioxide removal rate and sodium bicarbonate purity are shown in Table 2 above.

Comparative Example 2 is a result in a state in which the diffusion plate 15 is installed inside the reaction tank 10 under the same conditions as those of Comparative Example 1. Due to the installation of the diffusion plate 15, the yield of sodium bicarbonate is improved, and in particular, the carbon dioxide removal rate is particularly increased.

In Comparative Example 2, the gas bubbles were dispersed by the diffusion plate 15, and the reaction efficiency was increased. That is, before the diffusion plate 15 was installed, the bubble diameter was 1 cm to 2 cm, but after the diffusion plate 15 was applied, the bubble diameter decreased to 0.3 mm to 0.7 mm.

At this time, since the rising rate of the bubble is inversely proportional to the square of the diameter, the rising rate is reduced to about 1/10, and accordingly, the residence time of the bubble in the reactor is increased by about 10 times. The diffusion plate 15 not only increases the surface area by refining the air bubbles, but also the effect of increasing the residence time can be confirmed. Accordingly, the carbon dioxide removal rate increased by about 4%.

Comparative Example 3 is an example in which the washing process was additionally performed using pure water as a washing solution in Comparative Example 2.

In Comparative Example 3, when the produced sodium bicarbonate slurry was washed and dried, it can be seen that the purity was increased by 2 percentage points compared to Comparative Example 1 in which the slurry was dried without washing. However, the final production yield was partially reduced because sodium bicarbonate and raw material sodium carbonate were partially dissolved during washing.

In Comparative Example 4, the supply rate of the aqueous sodium carbonate solution supplied to the reaction tank 10 was lowered to 35 mL/min, and sodium carbonate was further dissolved to a concentration of 30 wt% in the washing solution of Comparative Example 3 and added to 35 mL/min. provided example.

In Comparative Example 4, when the raw material sodium carbonate was additionally dissolved in the washing solution and used for the reaction, the yield of sodium bicarbonate was increased compared to Comparative Example 3.

Comparative Example 5 is an example in which an aqueous solution of 7.7 wt% of sodium bicarbonate was prepared from the sludge obtained by dehydrating the sodium bicarbonate produced in Comparative Example 2 and washed.

Comparative Example 5 is the same as Comparative Example 3, but dissolution of the product can be prevented by using a sodium bicarbonate solution as a washing solution. As a result, it can be seen that the purity of sodium bicarbonate is 98%, which is increased compared to Comparative Example 1, but the purity is slightly decreased by about 1% compared to the case of washing with pure water as in Comparative Example 3.

In Comparative Example 6, the 35 wt% sodium carbonate aqueous solution was supplied in Comparative Example 2, the flow rate was lowered to 35 mL/min, and sodium carbonate was further dissolved in the washing solution used in Comparative Example 5 to 7.7 wt% sodium bicarbonate, sodium carbonate This is the result of preparing a washing solution with a solution of 5.6 wt% and additionally supplying it at a flow rate of 10 mL/min.

In Comparative Example 6, the washing solution used in Comparative Example 5 was made into a saturated solution of sodium carbonate and sodium bicarbonate, and then injected into the reactor again. It can be confirmed that the sodium bicarbonate production yield was increased by 5% in Comparative Example 6 as compared with Comparative Example 5.

1: Sodium bicarbonate manufacturing device
10: reaction tank
11: solution inlet
12: gas inlet
13: gas outlet
14: slurry outlet
15: diffuser plate
16: circulation line
21 : cooler
22: moisture remover
23: heat exchanger
S110: sodium carbonate aqueous solution introduction step
S120: gas cooling stage
S130: moisture removal step
S140: gas inlet step
S150: reactant heating step
S160: Slurry washing step

Claims (22)

reactor;
a solution inlet through which an aqueous sodium carbonate solution is introduced into the upper portion of the reactor from the outside;
a gas inlet through which a gas containing carbon dioxide is introduced from an exhaust line through which combustion exhaust gas is discharged to a lower portion of the reaction tank; and
a diffusion plate disposed in the reaction tank; and
In the reactor, the sodium carbonate aqueous solution flows from the top to the bottom, and the gas flows from the bottom to the top to form sodium bicarbonate, which is a reactant of the sodium carbonate and the carbon dioxide,
The diffusion plate is an apparatus for producing high purity sodium bicarbonate using exhaust gas, characterized in that the upper part is closed and the width is formed to widen toward the lower part in order to adjust the speed so that the gas rises and to disperse the precipitated sodium bicarbonate sludge. According to claim 1,
the height of the reactor
High-purity sodium bicarbonate manufacturing apparatus using an exhaust gas, characterized in that it is formed to be 10 to 20 times the width or diameter of the reactor. According to claim 1,
High-purity sodium bicarbonate manufacturing apparatus using flue gas, characterized in that a gas outlet through which the gas from which the carbon dioxide has been removed is formed higher than the solution inlet in the reaction tank. According to claim 1,
High-purity sodium bicarbonate manufacturing apparatus using flue gas, characterized in that a slurry outlet through which the slurry containing the sodium bicarbonate is discharged is formed at the lower end of the reactor. According to claim 1,
High-purity sodium bicarbonate manufacturing apparatus using flue gas, characterized in that the concentration of the sodium carbonate aqueous solution introduced into the solution inlet is 30% to 40%. According to claim 1,
Between the exhaust line and the gas inlet,
High-purity sodium bicarbonate manufacturing apparatus using flue gas, characterized in that the cooler for cooling the gas, and a water remover for removing moisture contained in the gas that has passed through the cooler are provided in order. delete According to claim 1,
The diffusion plate is an apparatus for producing high-purity sodium bicarbonate using exhaust gas, characterized in that a plurality of diffusion plates are arranged parallel to each other along a direction perpendicular to the longitudinal direction of the reactor. According to claim 1,
The diffusion plate is a high-purity sodium bicarbonate manufacturing apparatus using an exhaust gas, characterized in that arranged to be stacked in a plurality of stages along the longitudinal direction of the reactor. 10. The method of claim 9,
The upper and lower diffusion plates are vertically adjacent to each other, characterized in that the high-purity sodium bicarbonate manufacturing apparatus using an exhaust gas, characterized in that arranged to cross each other. 10. The method of claim 9,
A circulation line for circulating a portion of the solution filled in the reaction tank is formed on one side of the reaction tank,
High-purity sodium bicarbonate manufacturing apparatus using exhaust gas, characterized in that a heat exchanger for heating the solution circulating in the circulation line is installed in the circulation line. 12. The method of claim 11,
The heat exchanger is an apparatus for producing high-purity sodium bicarbonate using an exhaust gas, characterized in that heating the solution to 40 ℃ to 45 ℃. According to claim 1,
The diffusion plate becomes wider toward the lower part, and the high purity sodium bicarbonate production apparatus using exhaust gas, characterized in that the reaction between the aqueous sodium carbonate solution and the carbon dioxide diffused by the diffusion plate is increased. A sodium carbonate aqueous solution inflow step of introducing an aqueous sodium carbonate solution into the reactor through the upper part of the reaction tank disposed therein, and
A gas introduction step of introducing a gas containing carbon dioxide discharged through an exhaust line through which combustion exhaust gas is discharged into the inside of the reaction tank through the lower part of the reaction tank,
In the reaction tank, the sodium carbonate aqueous solution and the carbon dioxide are flowed in opposite directions to prepare sodium bicarbonate, which is a reactant of the sodium carbonate and the carbon dioxide,
A method for producing high-purity sodium bicarbonate using an exhaust gas, characterized in that increasing the reaction between the aqueous sodium carbonate solution and the carbon dioxide diffused by the diffusion plate. 15. The method of claim 14,
After the step of introducing the sodium carbonate aqueous solution,
High-purity sodium bicarbonate manufacturing method using exhaust gas, characterized in that it further comprises a gas cooling step of cooling the gas flowing into the reactor. 16. The method of claim 15,
After the gas cooling step,
High-purity sodium bicarbonate manufacturing method using exhaust gas, characterized in that it further comprises a water removal step of removing the water contained in the cooled gas. 15. The method of claim 14,
A method for producing high-purity sodium bicarbonate using an off-gas, characterized in that the concentration of the aqueous sodium carbonate solution introduced in the sodium carbonate aqueous solution introduction step is 30% to 40%. 15. The method of claim 14,
After the gas inlet step,
High-purity sodium bicarbonate manufacturing method using flue gas, characterized in that it further comprises a reactant heating step of heating the reactant with a heat exchanger installed in the circulation line while circulating the reactant inside the reaction tank through a circulation line. 19. The method of claim 18,
The reactant heating step is a method for producing high-purity sodium bicarbonate using an off-gas, characterized in that heating the reaction tank to 40 ℃ to 45 ℃. 15. The method of claim 14,
Method for producing high purity sodium bicarbonate using flue gas, characterized in that it further comprises a slurry washing step of washing the slurry containing the sodium carbonate generated inside the reactor. 21. The method of claim 20,
The slurry washing step is a method for producing high-purity sodium bicarbonate using an exhaust gas, characterized in that washing with an aqueous sodium bicarbonate solution. 22. The method of claim 21,
The sodium bicarbonate aqueous solution is a high-purity sodium bicarbonate manufacturing method using flue gas, characterized in that the weight ratio of sodium bicarbonate to the weight of the total aqueous solution is 7.7%.

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